Four alleged militants have been killed after a suspected US drone fired missiles at a house and a vehicle in north-western Pakistan, Pakistani intelligence officials said.

The attack could signal that the programme is picking up steam after strained relations halted strikes late last year.

The US suspended drone attacks in Pakistan for nearly two months after American air strikes accidentally killed 24 Pakistani soldiers at two posts along the Afghan border on November 26.

The deaths outraged Pakistan, which retaliated by closing its border crossings to supplies meant for Nato troops in Afghanistan and kicking the US out of a base used by American drones.

US drone attacks have been a source of tension between the two countries.

Although Pakistan is widely believed to have supported the strikes in the past, that co-operation has become strained as the relationship between the two countries has deteriorated.

The US halted strikes until January 10, when missiles hit a house in the North Waziristan tribal area in an attack that American officials said killed a key al Qaida operations planner, Aslam Awan. The US carried out another attack two days later.

The strike in North Waziristan's Deegan village was the third since the attacks resumed.